A predominant model for expert consultation systems is one in which a computer program simulates the decision making processes of an expert. The expert system typically collects data from the user and renders a solution. Experience with regular physician use of ONCOCIN, an expert system that assists with the treatment of cancer patients, has revealed that system users can be annoyed by this approach. In an attempt to overcome this barrier to system acceptance, ONCOCIN has been adapted to accept, analyze, and critique a physician's own therapy plan. A critique is an explanation of the significant differences between the plan that would have been proposed by the expert system and the plan proposed by the user. The critique helps resolve these differences and provides a less intrusive method of computer-assisted consultation because the user need not be interrupted in the majority of cases - those in which no significant differences occur. Extensions of previous rule-based explanation techniques has been required to generate critiques of this type.